Three-electrode sodium ion battery and manufacturing method thereof

Abstract

The invention discloses a manufacturing method of a three-electrode sodium ion battery, which comprises the following steps of: respectively scraping grooves with preset shapes and depths on a positive plate and a negative plate at corresponding positions on opposite sides of the positive plate and the negative plate to form a positive groove and a negative groove; the positive plate and the negative plate are laminated, so that the positive groove and the negative groove are spliced to form a reference electrode cavity with a side opening; a reference electrode is inserted into the formed reference electrode cavity, an electrode terminal is led out, and electrolyte is prepared. According to the manufacturing method of the sodium ion battery, the cycling stability and the energy density of the battery can be remarkably improved, and the manufactured sodium ion battery shows better performance and longer service life in the charging and discharging process, so that the reliability and the practicability of the battery are enhanced, and the power and the energy density are also improved.

Description

Technical Field

[0001] The invention belongs to the technical field of three-electrode sodium ion battery preparation process, and relates to a three-electrode sodium ion battery and a preparation method thereof. Background Art

[0002] As a new type of energy storage technology, sodium-ion batteries have developed rapidly in recent years due to their low material cost, good low-temperature performance, long cycle life and good safety performance. With the increasing global demand for renewable energy and large-scale energy storage technology, sodium-ion battery technology has attracted much attention due to its unique advantages.

[0003] The main structure of the three-electrode sodium-ion battery is designed to more accurately study and monitor the electrochemical process inside the battery, especially to independently measure the performance of the positive and negative electrodes. Its main structure includes a working electrode, a counter electrode, a reference electrode, and an electrolyte. The common positive electrode material is NaFePO 4 , but using NaFePO 4 The energy density of batteries prepared as positive electrode materials is low, and the existing electrolyte has the problem of low conductivity, which will affect the overall performance and service life of the final battery. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a three-electrode sodium ion battery and a method for manufacturing a three-electrode sodium ion battery, which can effectively solve the problems of low overall performance and short service life of the three-electrode sodium ion battery in the prior art.

[0005] Technical solution: A method for manufacturing a three-electrode sodium ion battery of the present invention comprises the following steps:

[0006] S1. Preparing grooves: on the opposite sides of the positive electrode sheet and the negative electrode sheet, at corresponding positions, respectively scraping grooves of a preset shape and depth on the positive electrode sheet and the negative electrode sheet to form positive electrode grooves and negative electrode grooves;

[0007] S2: stacking to form a reference electrode cavity: stacking the positive electrode sheet and the negative electrode sheet so that the positive electrode groove and the negative electrode groove are joined to form a reference electrode cavity with a side opening;

[0008] S3: Inserting a reference electrode and preparing an electrolyte: inserting an adapted reference electrode into the formed reference electrode cavity, leading out the electrode terminal, and preparing an electrolyte at the same time; the reference electrode adopts a foam metal skeleton, and the foam metal skeleton is filled with excess metallic lithium powder, and then the foam metal skeleton containing lithium powder is heated to melt the lithium powder and penetrate into the pores of the foam metal to form a lithium metal reference electrode.

[0009] Furthermore, the positive electrode sheet is doped with 5-50% lithium iron phosphate.

[0010] Furthermore, 0.1M-0.5M lithium hexafluorophosphate is added to the electrolyte in S3.

[0011] Furthermore, the porosity of the foam metal skeleton is 90-99%, and the pore size distribution range is 200-500 um.

[0012] Furthermore, after the foam metal is cooled, the filling and heating process is repeated until all pores of the foam metal are tightly filled with the molten and cooled lithium element, and then the excess lithium powder exceeding the outer contour of the foam metal is removed.

[0013] Furthermore, a foam metal filled with lithium is inserted into the reference electrode cavity, and the electrode terminal is led outward, and then the positive electrode sheet, the negative electrode sheet and the reference electrode are wrapped with a diaphragm to form a three-electrode structure.

[0014] Furthermore, the reference electrode in S3 is made of a thin lithium metal sheet, nickel TAB or lithium-aluminum alloy wire.

[0015] The present invention provides a three-electrode sodium ion battery, which is manufactured by adopting the manufacturing method of the sodium ion battery.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. The present invention significantly improves the cycle stability and energy density of the battery by doping 5-50% lithium iron phosphate in the positive electrode sheet. Therefore, the sodium ion battery exhibits better performance and longer service life during the charge and discharge process, which not only enhances the reliability and practicality of the battery, but also improves the power and energy density.

[0017] 2. The present invention optimizes the conductivity and stability of the electrolyte by adding 0.1M-0.5M lithium hexafluorophosphate into the electrolyte. As a commonly used lithium salt, the addition of lithium hexafluorophosphate improves the charge and discharge efficiency of the battery and enhances the stability of the battery under different temperatures and use conditions, thereby improving the overall performance and service life of the battery.

[0018] 3. The present invention adopts a foam metal skeleton as a reference electrode, with a porosity of 90-99% and a pore size distribution range of 200-500um. This design increases the surface area of ​​the reference electrode and improves its electrochemical activity while maintaining a lightweight structure, which is of great significance for improving the response speed and measurement accuracy of the battery, and ensures the accuracy and reliability of the battery test and measurement results.

[0019] 4. The present invention ensures the uniformity and consistency of the reference electrode by repeating the filling and heating process until all the pores of the foam metal are tightly filled with molten and cooled lithium powder and then removing the excess lithium powder beyond the outer contour of the foam metal. This step improves the electrochemical properties of the reference electrode, allowing the battery to maintain stable performance during long-term operation and reducing battery performance fluctuations caused by inconsistent reference electrode quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the process of the production method of the present invention. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0022] Embodiment 1, the present invention relates to a method for manufacturing a three-electrode sodium ion battery, the method comprising the following steps:

[0023] S1: Preparation of grooves: Scrape out grooves of preset shape and depth at corresponding positions on the opposite sides of the positive and negative electrode sheets to form positive and negative electrode grooves. These grooves are designed to form reference electrode cavities in subsequent steps to ensure that the reference electrode can be adapted and placed correctly.

[0024] By controlling the shape and depth of the groove, it is possible to ensure that the size and shape of the reference electrode cavity perfectly matches the reference electrode, thereby improving the precision and consistency of battery assembly. This precision is critical to the long-term stability and performance of the battery because it can reduce battery performance degradation and potential safety risks caused by improper installation of the reference electrode.

[0025] S2: Stacking to form a reference electrode cavity: Stack the positive and negative electrodes so that the positive and negative electrode grooves are joined to form a reference electrode cavity with a side opening. This step is critical because it provides a stable space for the reference electrode, ensuring the integrity of the battery structure and the stability of the reference electrode.

[0026] S3: Inserting a reference electrode and preparing an electrolyte: inserting an adapted reference electrode into the formed reference electrode cavity, and leading out the electrode terminal, and preparing the electrolyte at the same time.

[0027] This step involves the physical installation of the reference electrode and the preparation of the electrolyte, providing the necessary conditions for the electrochemical performance testing and operation of the battery.

[0028] Example 2: Based on Example 1, this example further discloses a specific preparation process of a method for making a three-electrode sodium ion battery.

[0029] Furthermore, the positive electrode sheet is doped with 5-50% lithium iron phosphate.

[0030] This doping can improve the cycle stability and energy density of the battery, making the sodium-ion battery exhibit better performance and longer service life during the charge and discharge process. It can significantly improve the cycle stability and energy density of the battery.

[0031] The doping of lithium iron phosphate not only improves the battery's charge and discharge efficiency, but also enhances the battery's performance in high and low temperature environments, enabling sodium-ion batteries to be used in a wider range of application scenarios.

[0032] Lithium iron phosphate (LiFePO 4 ) is an olivine-type positive electrode material that has attracted attention due to its structural stability and good electrochemical performance. Among the positive electrode materials for sodium-ion batteries, olivine-type sodium iron phosphate (NaFePO 4 ) has attracted much attention due to its similar structural characteristics. Doping lithium iron phosphate can improve the structural stability of the positive electrode material of sodium ion batteries, thereby enhancing the cycle stability and electrochemical performance of the battery. The discharge capacity of the doped and modified battery under 0℃ and -20℃ test conditions remains at 89.7% and 63.1% of the initial discharge capacity at room temperature, respectively.

[0033] Furthermore, 0.1M-0.5M lithium hexafluorophosphate is added to the electrolyte in S3.

[0034] As a commonly used lithium salt, the addition of lithium hexafluorophosphate can optimize the conductivity and stability of the electrolyte, thereby improving the overall performance of the battery.

[0035] Furthermore, the reference electrode in S3 uses a foam metal skeleton, the porosity of the foam metal skeleton is 90-99%, and the pore size distribution range is 200-500um.

[0036] The use of a foam metal skeleton can increase the surface area of ​​the reference electrode and improve its electrochemical activity while keeping the structure lightweight.

[0037] Furthermore, in S3, the foam metal skeleton is filled with excess metallic lithium powder, and then the foam metal skeleton containing the lithium powder is heated so that the lithium powder melts and penetrates into the pores of the foam metal to form a lithium metal reference electrode.

[0038] This preparation method can ensure that the reference electrode has good conductivity and chemical stability.

[0039] Furthermore, after the metal foam is cooled, the filling and heating process is repeated until all pores of the metal foam are tightly filled with the molten and cooled lithium element, and then the excess lithium powder exceeding the outer contour of the metal foam is removed.

[0040] This step ensures the uniformity and consistency of the reference electrode, improving its electrochemical performance.

[0041] Furthermore, a foam metal filled with lithium is inserted into the reference electrode cavity, and the electrode terminal is led outward, and then the positive electrode sheet, the negative electrode sheet and the reference electrode are wrapped with a diaphragm to form a three-electrode structure.

[0042] This step completes the assembly of the three-electrode structure and provides the basis for battery testing and use.

[0043] Furthermore, the reference electrode in S3 is made of thin lithium metal sheets, including but not limited to nickel TAB, lithium-aluminum alloy wire, inserted into the battery to achieve accurate electrochemical measurements.

[0044] Using a thin lithium metal sheet as a reference electrode can provide a more precise potential reference, thereby improving the accuracy of battery performance testing.

[0045] Comparative Example 1, for the traditional three-electrode preparation method, includes the following basic steps:

[0046] S1: Use copper wire to insert into the sodium battery;

[0047] S2: making the third electrode by sodium plating;

[0048] S3: Additional lithium plating on the copper wire.

[0049] In the traditional method, when making sodium ion three electrodes, copper wire is usually inserted into the battery. This method is simple and direct, but it cannot accurately control the position and shape of the third electrode, which affects the overall performance and stability of the battery.

[0050] At the same time, although the method of plating sodium on copper wire can form electrodes, there are problems with the small amount of lithium metal and its rapid consumption, which causes the accuracy and stability of the three electrodes to decrease over time.

[0051] Furthermore, the additional step of plating lithium on the copper wire increases the complexity and cost of the preparation, and also brings additional safety risks, because lithium is highly active and improper handling can easily cause safety problems.

[0052] The accuracy and stability of the three electrodes prepared in this way will decrease over time, and they will not be able to provide optimal electrochemical performance in daily use, which limits the overall performance of the battery, increases costs, and makes the preparation process more complicated, which is not conducive to large-scale production.

[0053] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for manufacturing a three-electrode sodium ion battery, characterized in that: The following steps are involved: S1. Preparing grooves: on the opposite sides of the positive electrode sheet and the negative electrode sheet, at corresponding positions, respectively scraping grooves of a preset shape and depth on the positive electrode sheet and the negative electrode sheet to form positive electrode grooves and negative electrode grooves; S2: stacking to form a reference electrode cavity: stacking the positive electrode sheet and the negative electrode sheet so that the positive electrode groove and the negative electrode groove are joined to form a reference electrode cavity with a side opening; S3: Inserting a reference electrode and preparing an electrolyte: inserting an adapted reference electrode into the formed reference electrode cavity, leading out the electrode terminal, and preparing an electrolyte at the same time; the reference electrode adopts a foam metal skeleton, and the foam metal skeleton is filled with excess metallic lithium powder, and then the foam metal skeleton containing lithium powder is heated to melt the lithium powder and penetrate into the pores of the foam metal to form a lithium metal reference electrode.

2. The method for manufacturing a three-electrode sodium ion battery according to claim 1, characterized in that: The positive electrode sheet is doped with 5-50% lithium iron phosphate.

3. The method for manufacturing a three-electrode sodium ion battery according to claim 1, characterized in that: 0.1M-0.5M lithium hexafluorophosphate is added to the electrolyte in S3.

4. The method for manufacturing a three-electrode sodium ion battery according to claim 1, characterized in that: The porosity of the foam metal skeleton is 90-99%, and the pore size distribution range is 200-500um.

5. The method for manufacturing a three-electrode sodium ion battery according to claim 1, characterized in that: After the foam metal is cooled, the filling and heating process is repeated until all pores of the foam metal are tightly filled with the molten and cooled lithium element, and then the excess lithium powder exceeding the outer contour of the foam metal is removed.

6. The method for manufacturing a three-electrode sodium ion battery according to claim 1 or 5, characterized in that: The foam metal filled with lithium is inserted into the reference electrode cavity, and the electrode terminal is led outward, and then the positive electrode sheet, the negative electrode sheet and the reference electrode are wrapped with a diaphragm to form a three-electrode structure.

7. The method for manufacturing a three-electrode sodium ion battery according to claim 1, characterized in that: The reference electrode in S3 is a thin lithium metal sheet, nickel TAB or lithium-aluminum alloy wire.

8. A three-electrode sodium ion battery, characterized in that: The three-electrode sodium ion battery is prepared by the method for preparing the three-electrode sodium ion battery according to any one of claims 1 to 7.

Images